feat(payouts): implement promoter earnings viewing, request flow, and admin Stripe processing with webhooks

Add model methods for accurate net calculations (€0.50 + 1.5% fees), eligibility, refund handling
Update promoter/payouts controller for index (pending events), create (eligibility checks)
Integrate admin processing via Stripe::Transfer, webhook for status sync
Enhance views: index pending cards, events/show preview/form
Add comprehensive tests (models, controllers, service, integration); run migrations

test/models/payout_test.rb

@@ -0,0 +1,109 @@
+require "test_helper"
+
+class PayoutTest < ActiveSupport::TestCase
+  setup do
+    @payout = payouts(:one)
+    @user = users(:one)
+    @event = events(:concert_event)
+  end
+
+  test "should be valid" do
+    assert @payout.valid?
+  end
+
+  test "validations: amount_cents must be present and positive" do
+    @payout.amount_cents = nil
+    assert_not @payout.valid?
+    assert_includes @payout.errors[:amount_cents], "can't be blank"
+
+    @payout.amount_cents = 0
+    assert_not @payout.valid?
+    assert_includes @payout.errors[:amount_cents], "must be greater than 0"
+
+    @payout.amount_cents = -100
+    assert_not @payout.valid?
+    assert_includes @payout.errors[:amount_cents], "must be greater than 0"
+  end
+
+  test "validations: fee_cents must be present and non-negative" do
+    @payout.fee_cents = nil
+    assert_not @payout.valid?
+    assert_includes @payout.errors[:fee_cents], "can't be blank"
+
+    @payout.fee_cents = -100
+    assert_not @payout.valid?
+    assert_includes @payout.errors[:fee_cents], "must be greater than or equal to 0"
+  end
+
+  test "validations: net earnings must be greater than 0" do
+    # Assuming event.net_earnings_cents is a method that calculates >0
+    @event.earnings.create!(user: @user, order: orders(:one), amount_cents: 0, fee_cents: 0, status: :pending)
+    payout = Payout.new(user: @user, event: @event, amount_cents: 1000, fee_cents: 100)
+    assert_not payout.valid?
+    assert_includes payout.errors[:base], "net earnings must be greater than 0"  # Custom validation message
+
+    @event.earnings.first.update(amount_cents: 2000)
+    assert payout.valid?
+  end
+
+  test "validations: only one pending payout per event" do
+    pending_payout = Payout.create!(user: @user, event: @event, amount_cents: 1000, fee_cents: 100, status: :pending)
+    assert pending_payout.valid?
+
+    duplicate = Payout.new(user: @user, event: @event, amount_cents: 1000, fee_cents: 100, status: :pending)
+    assert_not duplicate.valid?
+    assert_includes duplicate.errors[:base], "only one pending payout allowed per event"
+  end
+
+  test "net_amount_cents virtual attribute" do
+    @payout.amount_cents = 10000
+    @payout.fee_cents = 1000
+    assert_equal 9000, @payout.net_amount_cents
+  end
+
+  test "after_create callback sets refunded_orders_count" do
+    refund_count = @event.orders.refunded.count  # Assuming orders have refunded status
+    payout = Payout.create!(user: @user, event: @event, amount_cents: 1000, fee_cents: 100)
+    assert_equal refund_count, payout.refunded_orders_count
+  end
+
+  test "associations: belongs to user" do
+    association = Payout.reflect_on_association(:user)
+    assert_equal :belongs_to, association.macro
+  end
+
+  test "associations: belongs to event" do
+    association = Payout.reflect_on_association(:event)
+    assert_equal :belongs_to, association.macro
+  end
+
+  test "status enum" do
+    assert_equal 0, Payout.statuses[:pending]
+    assert_equal 1, Payout.statuses[:processing]
+    assert_equal 2, Payout.statuses[:completed]
+    assert_equal 3, Payout.statuses[:failed]
+
+    @payout.status = :pending
+    assert @payout.pending?
+
+    @payout.status = :completed
+    assert @payout.completed?
+  end
+
+  test "pending scope" do
+    pending = Payout.create!(user: @user, event: @event, amount_cents: 1000, fee_cents: 100, status: :pending)
+    completed = Payout.create!(user: @user, event: @event, amount_cents: 2000, fee_cents: 200, status: :completed)
+
+    assert_includes Payout.pending, pending
+    assert_not_includes Payout.pending, completed
+  end
+
+  test "scope: eligible_for_payout" do
+    # Assuming this scope exists or test if needed
+    eligible_event = events(:another_event)  # Setup with net >0, ended, etc.
+    ineligible = events(:ineligible)
+
+    eligible_payouts = Payout.eligible_for_payout
+    assert_includes eligible_payouts, eligible_event.payouts.first if eligible_event.can_request_payout?
+  end
+end